Channel letter coil is used in the production of illuminated signs that are most often associated with commercial enterprises such as restaurants, stores, and other businesses. Channel letter coil usually comprises a roll of readily formable metal (e.g., thin aluminum). A sign manufacturer takes the channel letter coil and, using a number of tools and methods, forms it into troughs (or channels) disposed upon or within the sign. These channels generally have the shape of particular individual characters (e.g., letters, numbers, symbols). A specialized light source (e.g., neon tubing or LEDs) of a desired shape or configuration is typically then disposed within the channel, and the channel and light may then optionally be covered over by some sort of protective or decorative lens, such as acrylic or film.
Conventionally, the coil material is supplied with a protective coating pre-applied to its surfaces for primarily aesthetic purposes but also, in part, to improve durability during handling, processing, and use. Typically, however, this pre-applied coating comprises a single layer of nominal thickness. Such conventional pre-applied coatings often do not, and are not intended to, enhance the performance or usability of the coil material as used in a finished channel coil sign product.
Manufacturers of finished channel coil sign products therefore often must, or choose to, apply additional coatings to enhance the durability and reflectivity of the channel coil. In some instances (e.g., outdoor signs) additional coatings may also be added to protect the interior of the sign from damaging outdoor conditions. Most often, however, additional coatings are applied to the backside (i.e., inner surface) of the channel coil to increase the effective intensity of the light emitted from the sign, without increasing its required power usage. Otherwise, the sign manufacturer may have to position additional light sources within the channel to achieve the desired illumination.
Exterior coatings may also be applied—as or to the topcoat—to provide various aesthetic effects (e.g., color). Although rolled coil material is typically supplied with some basic pre-painting, as previously noted, these special additional coatings are usually not applied to the coil material until after it has been unrolled and formed into its desired shape. This conventional type of application adds cost and inefficiency into the production process.